<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			div {
				opacity: .5;
				/*兼容IE8及以下*/
				filter: alpha(opacity=50); 
			}
		</style>
	</head>
	<body>
		<div id="book">
			透明度
		</div>
	</body>
</html>
